Asphalt recycling system and method for producing a new asphalt layer from the asphalt to be recycled

ABSTRACT

A hot asphalt recycling system, in order to obtain RAC, which is to be used in the production of one of the asphalt layers, from RAP material, characterized by comprising an inner air channel ( 25 ) which is positioned in the inner volume of the body ( 20 ), connects an air inlet pipe ( 241 ) which provides the primary hot air input to the body ( 20 ) to the said outer air channel ( 24 ) and at least a section of which extends at the vicinity of the transmission line ( 23 ) and a mixer ( 50 ) wherein the RAP, which is at the desired amount and which comes from the discharge mechanism ( 27 ), new bitumen at a predetermined amount and optionally at least one chemical additive are mixed for a predetermined period.

CROSS REFERENCE TO RELATED APPLICATIONS

This continuation application claims benefit of International PCT Patent Application No. PCT/EP2011/071680 filed Dec. 3, 2011, which is incorporated herein by reference in their entireties for all purposes.

TECHNICAL FIELD

The present invention relates to asphalt recycling systems which provide the asphalt layer (RAP), which is desired to be recycled by being removed from the place thereof, to be converted into recycled asphalt concrete (RAC), and particularly relates to asphalt recycling systems with respect to the prior art part of Claim 1.

BACKGROUND

As known, asphalt concrete obtained from the aggregate and bitumen mixture is used as different layers like corrosion layer, binder, straightening layer and base layers on road's upper structure. Each of these layers is produced by means of recipes prepared in laboratory with respect to the methods of international standards in order to provide different performance requirements. Different performances expected from each layer are provided by means of recipes prepared by different maximum particle dimension, different gradation and different bitumen proportions. These performance requirements are valid also for the layers to be realized using the recycled asphalt concrete (RAC).

Asphalt concrete which is applied to roads should be removed after certain usage. Today, because of the environmental conditions, removed asphalt concrete should be recycled and used in the production of new asphalt concrete. Moreover, recycling of the removed asphalt concrete (hereafter it will be called RAP) and the usage thereof in the production of new asphalt concrete provides economic advantages. As the proportion of removed asphalt used increases in the production of new asphalt concrete, the economic advantage provided increases more.

Thus, in the related technical field, recycling can be realized by the usage of removed (RAP) asphalt concrete in the production of new asphalt concrete. In the present art, there is a plurality of technological recycling methods used for the recycling of asphalt.

Whatever the recycling method, the recycling of the RAP and the proportion of the RAP in the new mixture depends on maximum granule dimension, gradation and the bitumen proportion included and the results of the measurement of the aging and fatigue characteristics of the bitumen included. The removed asphalt concrete can be added with the proportion that the new mixture can provide the desired performance characteristics.

The most frequent recycling method is the adding of the removed asphalt concrete, in cold form and in determined proportions to the new asphalt mixture realized in the asphalt plant mixer. This method is called cold recycling. With this method, the maximum recycling ratio which can be obtained is 20%. In another frequent recycling method, RAP is brought to the process temperature in a heating mechanism which operates in connection with a present asphalt plant and afterwards, the asphalt plant is added to the new mixture; this process is called hot recycling. With this method, in the beginning, the recycling ratio is greater than the recycling ratio of cold recycling, because of the disadvantages faced during the heating of the RAP in this system and during the advancing of RAP inside the system for feeding the RAP into the asphalt plant mixer, the recycling ratio decreases during usage.

One of the abovementioned disadvantages is that the bitumen inside the RAP is heated and as a result, it fluidizes and it becomes adhesive, and as a result of this, RAP adheres and deep draws to the media (media like heating drum and conveyor or elevator) realizing heating and transfer. As the operation continues, RAP which is deep drawn and adhered to the wall of the media decreases the efficiency (flow rate, heat, etc.) of the mechanism. Moreover, during operation, since the RAP adheres to the inner walls and since the RAP narrows the media it adheres, the RAP should be frequently cleaned, and therefore the mechanism should be stopped and cooled. This decreases the efficiency of the system. The second disadvantage is that since the asphalt plant is heated in a free manner before it is added to the new mixture in the mixer, and moreover during the transferring of this asphalt plant to the mixture, the homogeneity of the mixture is deteriorated and this homogeneity can not be provided again. Another disadvantage is that in the present hot recycling methods, during heating, the hot air obtained from a heat source (burner) and the RAP which comprises bitumen strike directly and instantly. This situation leads to the deterioration of the bitumen inside the RAP, which is already aged and fatigue.

Another important disadvantage is related to the chemical additives used. As known, thanks to the different chemical additive substances, the RAP is improved which was deteriorated because of aging and fatigue, thus, RAC with higher performance with a higher level of recycling can be obtained. In order to realize the desired affect on the RAP, these chemical additives, which are desired to be affective on RAP, should be used by taking into consideration whole of the mixture, in other words, said chemical additives should have bigger proportions in the mixture.

As a solution to the abovementioned problems, the applicant provided the patent application WO2009058103. In this application, a system is disclosed which has at least 3 edges and which has a body with a transmission channel extending along the periphery. Accordingly, RAP is moved along the periphery of the body by means of the pallets inside said transmission channel and meanwhile, it is subject to heat in order to have the required process temperature. After the desired process temperature is obtained, RAP is stored in an accumulation reservoir where the temperature thereof is preserved and it is automatically transferred to the asphalt plant mixer where new asphalt concrete production is realized. Thus, recycling can be obtained with the bringing of the RAP to the process temperature by means of an efficient and homogeneous heating and with the addition of the required additives.

However, using this novel and advantageous system, in order to produce RAC from RAP, the system has to function in connection with an asphalt plant. As a result of the researches realized by the applicant, with novel revisions, this system is seen to be possible to be used in RAC production by operation independent of an asphalt plant.

SUMMARY

The present invention is a novel hot asphalt recycling system which eliminates the abovementioned disadvantages and which brings new advantages to the related technical field.

An object of the subject matter invention is to increase heating efficiency of the systems providing hot RAP to an asphalt plant in order to be used in new asphalt concrete production, thus, the object is to provide the usage of maximum proportion of RAP in the new asphalt mixture.

Another object of the subject matter invention is to produce RAC which will form the bitumen base, from the asphalt which is desired to be recycled (RAP) as independently of an asphalt plant.

In order to reach said objects, the present invention relates to a hot asphalt recycling system comprising a heat-insulated body with a closed volume; at least one RAP material transmission channel within said frame, said channel being embodied so as to produce a geometrical shape with at least three edges; a transmission line displacing within said RAP material transmission channel and comprising a plurality of transmission plates positioned thereon at certain intervals; an outer air channel which substantially encircles said transmission channel and wherein hot air is circulated; an accumulation reservoir which is formed inside the body and where the RAP at certain temperature is stored so as to preserve the temperature of the RAP; and a discharge unit which is used to discharge the hot RAP material within the accumulation reservoir to the desired media; in order to obtain RAC, which is to be used in the production of both of the asphalt layers (binder and bitumen base), from RAP material.

The system is characterized by comprising an inner air channel which is positioned in the inner volume of the body, connects an air inlet pipe which provides the primary hot air input to the body to the said outer air channel and at least a section of which extends at the vicinity of the transmission line; in order to lengthen the path the hot air takes inside the body and thus in order to transfer the heat, which is provided by the heat source and which circulates inside the body, to the RAP in an efficient manner.

Another improvement of the system is that the system comprises a mixer wherein the RAP coming from the discharge mechanism, new bitumen at a predetermined amount and optionally at least one chemical additive are mixed for a predetermined period; in order to produce RAC from the hot RAP, accumulated in the accumulation reservoir, as independently of an asphalt plant.

In a preferred embodiment of the present invention, at least some part of said inner air channel comprises parts extending together with the transmission channel so as to partly extend substantially parallel to the transmission channel.

In another preferred embodiment of the present invention, a horizontal part passes through said inner air channel's accumulation reservoir.

In another preferred embodiment of the present invention, said inner air channel comprises a lower part extending at the bottom part of the body; an vertical part extending so as to contact the transmission channel inwardly along a part of the vertical edge of the body at the continuation of the lower part; a horizontal part extending substantially horizontally at the continuation of said vertical part; and an output part which extends at the continuation of the horizontal part so as to connect the inner air channel to the outer air channel.

In another preferred embodiment of the present invention, in order to provide the hot air exiting from the outer air channel to be transferred to the body inner volume again, an intermediate connection part is provided which connects the output of said outer air channel to a heating reservoir formed at the inner volume of the body.

In another preferred embodiment of the present invention, said heating reservoir comprises at least one first and one second directing wings extending on said heating reservoir body inner volume.

In another preferred embodiment of the present invention, the first directing wing comprises a flat part at least extending along a part of the diagonal edge of the body so as to have a certain distance in between.

In another preferred embodiment of the subject matter system, said second directing wing which extends beginning from a point substantially at a lower alignment of the first directing wing and which extends up to the vicinity of the lower alignment of the accumulation reservoir base.

In another preferred embodiment of the subject matter system, a bitumen feeding unit is provided which is controlled by the automatic control system and thanks to this, which transfers new additional bitumen to the mixer in desired times and in desired amounts.

In another preferred embodiment of the present invention, at least one chemical feeding unit is provided which is controlled by the automatic control system and thanks to this, which transfers chemical additive to the mixer in desired times and in desired amounts.

In another preferred embodiment of the subject matter system, a directing unit is provided which directs the material exiting from said mixer to the RAC silo or to an asphalt plant.

In another preferred embodiment of the subject matter system, said directing unit comprises at least one silo output, at least one asphalt plant output and at least one flap which closes the silo output or asphalt plant output as responsive to the commands of the automatic control system.

In another preferred embodiment of the subject matter system, in order to prevent the RAP, which is heated and which becomes adhesive, from plastering to the inner walls of the transmission channel, said transmission plates have dimensions so as to advance by contacting substantially to the inner wall of the transmission channel.

In another preferred embodiment of the subject matter system, the subject matter system is operated independently from the asphalt plant and, the RAC, which is to be used in the production of bitumen base, is produced.

In another preferred embodiment of the subject matter system, in case of cooperation with asphalt plant; the RAC is produced which is to be used in the production of abrasion layer or binder.

The subject matter invention is a hot asphalt recycling method applied in order to obtain RAC by using RAP, where the RAP is to be used in the production of one of the asphalt layers by using RAP, characterized by comprising the steps of:

-   a) Providing a body with a closed volume which is thermally and     substantially insulated from the outer environment, -   b) advancing the RAP inside a transmission channel extending in a     direction so as to define at least three corners inside said body, -   c) during said advancing process, circulating the hot air obtained     from a hot air supply inside the inner volume of the body so as to     provide heat transfer to a certain part of the RAP inside the     transmission channel, -   d) Circulating the hot air along the outer circumference of the body     so as to provide heat transfer to a certain part of the RAP inside     the transmission channel, -   e) Circulating the hot air by directing the hot air inside the body     so as to provide heat transfer to the RAP directly and indirectly, -   f) Circulating the heated RAP inside the body so as to direct the     RAP to the accumulation reservoir, where the RAP is accumulated, -   g) Transferring the hot RAP inside the accumulation reservoir to a     mixer at a predetermined arrangement, -   h) Transferring new additional bitumen and optionally at least one     chemical additive to said mixer at a predetermined arrangement, -   i) Mixing the hot RAP material, new additional bitumen and     optionally at least one chemical additive for a predetermined     duration inside the mixer and discharging this mixture to the     desired outer environments.

In another preferred application of the subject matter method, in said step (c), the hot air is partly circulated at the vicinity of the transmission channel so as to be substantially parallel to the transmission channel.

In another preferred application of the subject matter method, in said step (c), hot air is passed through the accumulation reservoir.

In another preferred application of the subject matter method, in said step (e), hot air is circulated so as to advance along a certain part of the diagonal edge of the body.

In another preferred application of the subject matter method, with respect to the operation options with or without asphalt plant, in said step (j), the material exiting from the mixer is directed to a silo or an asphalt plant.

In another preferred application of the subject matter method, in case of operation independent of the asphalt plant, the RAC material which will form the bitumen base is produced.

In another preferred application of the subject matter method, in case of cooperation with the asphalt plant, the RAC material which will form the abrasion or binder layer is produced.

The structural and the characteristic features and all the advantages of the subject matter invention can be understood more precisely by means of the detailed explanation which is written with references to these figures and therefore, it had to be evaluated with the detailed explanation and figures that are explained below.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a representative view of the system where the subject matter asphalt recycling system is applied.

FIG. 2 a is the solo perspective view of the subject matter asphalt recycling system.

FIG. 2 b is the perspective view of the inner structure of the subject matter asphalt recycling system.

In FIGS. 3 a, 3 b, 3 c and 3 d, the views regarding the inner structure of the subject matter asphalt recycling system is given.

In FIGS. 4 a and 4 b, representative views regarding the operation of the subject matter asphalt recycling system with and without asphalt plant are given.

DETAILED DESCRIPTION OF THE INVENTION

In this detailed explanation, the subject matter hot asphalt recycling system is explained with references to figures without forming any restrictive effect in order to make the subject more understandable.

With reference to FIG. 1, hot air required for the subject matter hot asphalt recycling system (hereafter it will be called RS) is preferably provided by a hot air generator (70) which is preferably a burner. In this application of the subject matter invention, air which is provided by the hot air generator (70) and which is at 650° C. temperature is decreased to 400-450° C. by means of the air cooling system at the output of hot air generator (70). The hot air is given to RS from here by means of an air inlet pipe (241). Depending on the outer environment conditions, the temperature of the hot air advancing along the air inlet pipe (241), which is directly in contact with the outer environment, decreases until it reaches the RS inlet, for instance, in a preferred application, the air entering the RS has a temperature between 390-440° C.

The cold RAP material which will be processed in RS and the additional aggregate which is to be mixed with cold RAP material are transferred to the RS by means of a loading unit (10). At said loading unit (10), there is at least one additional aggregate silo (11), at least one cold RAP silo (12), a band conveyor (13) which is positioned under said silos (11, 12), and an vertical elevator (14) which is positioned at the end of the band conveyor (13). Said silos (11, 12) have dosaged feeding units (not illustrated in the figure) which are controlled by the automatic control unit of the RS. Thanks to this, with respect to the cold RAP and additional aggregate proportions which are to be used in the mixture determined by the methods whose details are given below, automatic control unit adjusts the amount of material to be transferred to the band conveyor (13). For instance, if 70% RAP material and 30% aggregate are to be used in the mixture, the dosaged feeding units of the RAP silo (12) and the aggregate silo (11) function with respect to these proportions, and thanks to this, material is fed to the band conveyor (13) with desired proportions continuously. As a result, the material on the band conveyor (13) is elevated to the feeding inlet (28) on the upper edge of the RS by means of said vertical elevator (14) and the material is transferred to the RS.

With reference to FIG. 2 a, the end part of the lower corner of the RS has a cross section like a cut vertical triangle and it comprises a body (20) with a heat insulated closed volume. The heating process of the RAP material is realized in said body (20). Accordingly, the hot air which enters into the body (20) through the air inlet pipe (241), preferably through a lateral surface of the body (20) is transferred to the cold RAP which is circulated inside the system in an efficient and homogeneous manner, and at the end of the process, the hot air is transferred to a filter (71) by means of an air output pipe (247) and from there, the hot air is transferred to the atmosphere. For instance, in a preferred embodiment, the air temperature which is between 390-440° C. at the inlet (241) decreases down to approximately 150-190° C. at the air output pipe (247).

With reference to FIGS. 3 a and 3 b, the RS has a transmission channel (21) which extends along the inner periphery of the body (20) and which preferably has a hollow rectangular cross-section. Said transmission channel (21) is ended (211) with the base part becoming open at a point close to the middle of the upper edge of the body (20), thus, the carried RAP material is accumulated in an accumulation reservoir (26) formed inside the body (20). Said accumulation reservoir (26) preferably has a cross section like an inverse trapezoid which substantially extends downwardly from the upper part of the body (20).

In more details, with reference to FIGS. 3 b and 3 c, there is a transmission line (23) inside the transmission channel (21), which circulates the cold RAP entering into the RS and which meanwhile provides the RAP to be subjected to heat as detailed below. Said transmission line (23) has a plurality of transmission plates (231) which are positioned one after another so as to have a certain space in between and which are positioned inside the transmission channel (21) so as to be substantially perpendicular with respect to the extension direction of the transmission channel (21). Thus, the RAP material which is advanced by the transmission plates (231) is circulated inside the transmission channel (21).

Said transmission plates (231) have dimensions so as to substantially contact with the inner wall of the transmission channel (21). Thanks to this, during circulation the transmission plates (231) strip the inner wall of the transmission channel (21) continuously, thus they strip the deeply drawn RAP which becomes adhesive as a result of the temperature, and they particularly strip the bitumen from the wall, thus, the accumulation of the bitumen on the wall is prevented and thereby the inefficiency in heat transfer is prevented. Thanks to this characteristic, the problem of decrease in heating efficiency as a result of adhesive RAP is eliminated, which is one of the biggest handicaps in the previous systems. Said transmission plates (231) are preferably connected onto chains (232) and said chains (232) are connected to chain gears (233) where each one is positioned to one corner of the body (20). Thus, when the chain gears (233) are rotated by means of a drive mechanism with a reducer (not illustrated in the figure) and by means of an electric motor which is controlled by the automatic control unit of the RS, the transmission line (23) begins moving inside the transmission channel (21). On the other hand, in alternative embodiments, different drive systems can also be used.

Again with reference to FIGS. 3 b and 3 c, the asphalt which is poured from the end of the vertical elevator (14) to the feeding inlet (28), and the cold RAP which is transferred to the transmission line (23) preferably by means of an asphalt feeding screw (not illustrated in the figure) are moved along the transmission channel (21), at the end of the transmission channel (21), they are discharged to the accumulation reservoir (26), from there they are transferred to a discharge unit with loadcell (27) from the hot RAP output (261) of the accumulation reservoir (26). In more details, in times determined by the automatic control system, the valve (not illustrated in the figure) at the hot RAP outlet (261) is opened and thus the hot RAP is poured to the discharge unit with loadcell (27). When the amount of hot RAP poured to the discharge unit with loadcell (27) reaches a certain weight (for instance 1750 kg), it is poured to the mixer (50). Said weight amount is defined in the memory of the automatic control system by being predetermined with respect to the asphalt type desired to be produced and with respect to similar variables.

In order for the abovementioned RS to be used in the production of at least bitumen base and moreover in the production of other asphalt layers without depending on an asphalt plant (90), the hot air provided by the hot air generator (70) should be transferred to the RAP, which is carried in the transmission channel (21), by indirect heating in the most efficient manner so as not to give damage to the structural properties of the bitumen. With respect to this, with reference to FIG. 2 b and FIG. 3 a, the circulation of the hot air inside the RS body (20) so as to be in correlation with RAP is provided by means of particularly designed outer and inner air channels (24, 25).

Accordingly, the air inlet pipe (241) is connected to an inner air channel (25) which is embodied on the inner volume of the body (20). Said inner air channel (25) comprises a lower part (251) which is positioned at the lower part of the body (20) and which has a U like cross section; an vertical part (252) which extends so as to contact with the transmission channel (21) inwardly along a part of the vertical edge of the body (20) at the continuation of the lower part (251); and a horizontal part (253) which essentially extends horizontally so as to pass through the accumulation reservoir (26) at the continuation of said vertical part (252); and an output part (254) which extends at the continuation of the horizontal part (253) in order to connect the inner air channel (25) to the outer air channel (24). Thanks to the special design of said inner air channel (25), the distance the hot air advances inside the body (20) is maximized and during this circulation, maximum heat transfer is provided to the transmission channel (21) and thus to the RAP.

The air exiting from the inner air channel (25) is transferred to the outer air channel (24) by means of a transmission pipe (248). Said outer air channel (24) extends along the outer periphery of the body (20) so as to contact with the transmission channel (21) outwardly at each point thereof. In more details, said outer air channel (24) essentially comprises an upper part (245) which extends along the upper edge of the body (20) by beginning from the region where the accumulation reservoir (26) begins; a diagonal part (243) which extends along the hypotenuse edge of the body (20) at the continuation of the upper part (245); a lower part (244) which extends along the short edge of the body (20); and an vertical part (242) which extends along the vertical edge of the body (20). With reference to FIGS. 2 b and 3 d, at the continuation of the upper part (245), there is an interconnection part (246) which extends parallel to the ground on the exterior of the lateral surface of the body (20) and which opens to a heating reservoir formed at the inner volume of the body (20) from the other end thereof. Thus, the hot air exiting from the outer air channel (24) is again transferred to the heating reservoir (22) in the opposite side.

Said heating reservoir (22) is defined by the first and second directing wings (221, 222). The first directing wing (221) extends so as to begin from the end of the transmission line (23) and so that there is a certain distance in between along the diagonal edge of the body (20). The second directing wing (222) extends to the lower alignment of the base of the accumulation reservoir (26) by beginning from a point on the diagonal edge of the body (20) and it extends at a substantially lower alignment of the first directing wing (221).

In more details, the first directing wing (221) has a curved part extending in a convex manner beginning from the end of the transmission line (23) and it has a flat part extending along the diagonal edge at the continuation thereof. The second directing wing (222) has a bending point in the middle region thereof so that the flaps thereof will define an open V shape and thanks to this, the second directing wing (222) extends towards the base of the accumulation chamber (26) with firstly a narrower angle with respect to the ground and secondly at an angle close to vertical. On the other hand, along the heating reservoir (22), the inner wall of the transmission channel (21) has an open structure in order to provide the direct contact of the hot air to the RAP. Thus, along the extension direction of the first directing wing (221), hot air directly contacts with the RAP, and afterwards, hot air is transferred to the lower side of the accumulation chamber (26) by means of the second directing wing (222). Thus, thanks to this characteristic and thanks to the inner air channel's (25) horizontal part (253) passing through the accumulation reservoir (26), the hot RAP (100) inside the accumulation reservoir (26) can continuously preserve the heat thereof.

In order to make the subject more understandable, the path the hot air follows is illustrated with arrows in FIGS. 3 a and 3 d, where hot air enters the body (20) through the air inlet pipe (241), it advances inside the body (20) along the inner air channel (25), afterwards it advances along the outer air channel (24), afterwards it is directed towards the heating reservoir (22) into the body (20), it moves inside the heating reservoir (22), and from there it advances to the accumulation reservoir (26), and it exits the body (20) by means of the air output pipe (247).

As a result, thanks to the particular design of the inner air channel (25) and thanks to the particular design of the outer air channel (24), much more efficient heat transfer can be realized to the RAP. Efficient heat transfer provides the hot RAP exiting from the RS to be at the desired temperature (preferably 120-130° C.), and independently of an asphalt plant (90), this provides the hot RAP (100) from RS to be processed as detailed below and provides the hot RAP (100) to be used as RAC which will form the bitumen base.

In order to provide this, in the subject matter invention, in addition to the abovementioned improvements, there is a mixer (50) at the lower alignment of the discharge unit with loadcell (27). In order to obtain the bitumen base, in addition to the hot RAP (100) exiting from the RS, additional new bitumen and when required, a plurality of chemical substances (for instance, abrasion-preventive chemical substances) which will improve the characteristics of the material should be added to the mixture. Therefore, a bitumen feeding unit (30) and a chemical feeding unit (40) transfer additional bitumen and chemical additives respectively in predetermined periods to said mixer (50). Thus in the mixer (50), hot RAP, new bitumen and optionally a mixture comprising the chemical additive are mixed for the desired duration. Both the bitumen feeding unit (30) and the chemical feeding unit (40) preferably comprise one each proportional pump (not illustrated in the figure) which is controlled by an automatic control system. Accordingly, prior to the process, the amount of bitumen and/or chemical substance to be added to the mixture is determined in the memory of the automatic control system and accordingly, the proportional pumps (not illustrated in the figure) are controlled.

On the other hand, the subject matter invention can be used together with an asphalt plant (90) when particularly binder or abrasion layer is desired to be produced, thanks to this, said asphalt layers can be produced by the asphalt plant (90) using the maximum possible proportion of RAP. Accordingly, at the output of said mixer (50), there is a directing unit (60). The directing unit (60) has at least one RAC silo outlet (61) and at least one asphalt plant outlet (62), and a flap (63) whose movement is controlled by the automatic control system closes one of these outlets (61, 62) according to the condition. In other words, when bitumen base is desired to be produced by operation independent of the asphalt plant, since only RS will be used, the asphalt plant outlet (62) is closed and the material exiting the mixer (50) is directly transferred to the silos (80) directly through the silo pipes. When binder or abrasion layer is desired to be produced by operating RS together with the asphalt plant, this time, the material exiting the mixer (50) is subject to additional processes, and this material is transferred to the asphalt plant's mixer (91) through the plant pipe.

The RAC which is to be used in asphalt layers is desired to have certain characteristics. These specifications are determined in national or international norms and these specifications also apply to the asphalt concrete (RAC) which is to be produced from RAP by means of RS.

In order to produce RAC without using RAP in the asphalt plant, a plurality of laboratory studies should be realized beforehand, and accordingly, first of all, the properties of aggregate and bitumen which are the raw materials used in production should be determined and accordingly, a mixture recipe should be prepared which will meet the performance properties of the asphalt layer in optimum level which is desired to be produced under certain process conditions. Different methods are used in recipe preparation; the most frequent method is the Marshall method.

Accordingly, by means of the recipe prepared in the laboratory, the gradation of the aggregate, which has certain physical, chemical and geometric properties and which is to be used as the raw material is determined which will provide the optimum performance characteristics (stability, practical-volume specific weight, void ratio, void filled with asphalt, VFA and flow criteria) expected from the asphalt concrete mixture and the bitumen proportion which will be added to the mixture is determined.

In order to produce RAC using RAP, laboratory study should be realized using the same method. Here, the only difference is that, when the abovementioned recipe is being prepared, the characteristics of the RAP to be used in the mixture are taken into account. The most important factor during the preparation of recipe for RAC is that the characteristics like penetration and smoothing point of the bitumen which RAP comprises are deteriorated because of the effects like fatigue and aging. The deteriorations in these characteristics are predetermined and these characteristics are improved by a plurality of chemical additives and they become optimum. Naturally, in RAC production, removed asphalt concrete is used with appropriate characteristics. The characteristics of the RAP material determine the usage ratio in RAC production. When the characteristics of RAP are better, the usage ratio of RAP material in the new mixture is higher. As a result of the studies realized in laboratory, different recycling proportions are obtained with different operating conditions. By taking these values into account, the subject matter asphalt recycling system is operated by being adapted to all of the different operating conditions.

In addition to the abovementioned details, in order to obtain a mixture appropriate to the criteria for producing one of the asphalt layers in the mixer (50), the automatic control system used in the subject matter invention essentially comprises cold RAP material which is to be heated inside the body (20); additional aggregate amount to be added to cold RAP; hot RAP (100) which is to be transferred to the mixer (50); additional new bitumen to be transferred to the mixer (50); and optionally the values regarding the chemical additive amount in the memory thereof; and with respect to said values, the subject matter invention controls the cold RAP silo (12), additional aggregate silo (11), band conveyor (13), discharge unit with loadcell (27), bitumen feeding unit (30) and optionally the chemical feeding unit (40) respectively. Said control system moreover controls the advancing speed of the transmission line (23), the temperature of the air used in the system, flow rate, the operation process of the mixer, and the timings and sequences of the processes mentioned in this paragraph. 

1. A hot asphalt recycling system comprising a heat-insulated body with a closed volume; at least one RAP material transmission channel within said body, said channel being embodied so as to produce a geometrical shape with at least three edges; a transmission line displacing within said RAP material transmission channel and comprising a plurality of transmission plates positioned thereon at certain intervals; an outer air channel which encircles said transmission channel substantially and wherein hot air is circulated; an accumulation reservoir which is formed inside the body and where the RAP at certain temperature is stored so as to preserve the temperature thereof; and a discharge unit which is used to discharge the hot RAP material within the accumulation reservoir to the desired media; in order to obtain RAC, which is to be used in the production of both of the asphalt layers (binder or bitumen base), from RAP material, characterized by comprising an inner air channel which is positioned in the inner volume of the body, connects an air inlet pipe which provides the primary hot air input to the body to the said outer air channel and at least a section of which extends at the vicinity of the transmission line, in order to lengthen the path the hot air takes inside the body and thus in order to transfer the heat, which circulates inside the body, to the RAP in an efficient manner. a mixer wherein the RAP coming from the discharge mechanism, new bitumen at a predetermined amount and optionally at least one chemical additive are mixed for a predetermined period; in order to produce RAC from the hot RAP, accumulated in the accumulation reservoir, as independently of an asphalt plant.
 2. The hot asphalt recycling system according to claim 1, characterized in that at least some part of said inner air channel comprises parts extending together with the transmission channel so as to partly extend substantially parallel to the transmission channel.
 3. The hot asphalt recycling system according to claim 1, characterized in that a horizontal part passes through said air channel's accumulation reservoir.
 4. The hot asphalt recycling system according to claim 1, characterized in that said inner air channel comprises a lower part extending at the bottom part of the body; an vertical part extending so as to contact the transmission channel inwardly along a part of the vertical edge of the body at the continuation of the lower part; a horizontal part extending substantially horizontally at the continuation of said vertical part; and an output part which extends at the continuation of the horizontal part so as to connect the inner air channel to the outer air channel.
 5. The hot asphalt recycling system according to claim 1, characterized in that in order to provide the hot air exiting from the outer air channel to be transferred to the body inner volume again, an intermediate connection part is provided which connects the output of said outer air channel to a heating reservoir formed at the inner volume of the body.
 6. The hot asphalt recycling system according to claim 5, characterized in that said heating reservoir comprises at least one first and one second directing wings extending on said heating reservoir body inner volume.
 7. The hot asphalt recycling system according to claim 6, characterized in that the first directing wing at least comprises a flat part extending at least along a part of the diagonal edge of the body so as to have a certain distance in between.
 8. The hot asphalt recycling system according to claim 6, characterized in that said second directing wing which extends beginning from a point substantially at a lower alignment of the first directing wing and which extends up to the vicinity of the lower part of the accumulation reservoir base.
 9. The hot asphalt recycling system according to claim 1, characterized in that a bitumen feeding unit is provided which is controlled by the automatic control system and thanks to this, which provides new additional bitumen to be transferred to the mixer in desired times and in desired amounts.
 10. The hot asphalt recycling system according to claim 1, characterized in that at least one chemical feeding unit is provided which is controlled by the automatic control system and thanks to this, which provides the transferring of chemical additive to the mixer in desired times and in desired amounts.
 11. The hot asphalt recycling system according to claim 1, characterized in that a directing unit is provided which directs the material exiting from said mixer to the RAC silo or to an asphalt plant.
 12. The hot asphalt recycling system according to claim 11, characterized in that said directing unit comprises at least one silo output, at least one asphalt plant output and at least one flap which closes the silo output or asphalt plant output as responsive to the commands of the automatic control system.
 13. The hot asphalt recycling system according to claim 1, characterized in that in order to prevent the RAP from sticking to the inner walls of the transmission channel where the RAP is heated and becomes adhesive, said transmission plates have dimensions so as to contact substantially to the inner wall of the transmission channel.
 14. The hot asphalt recycling system according to claim 1, characterized in that the subject matter system is operated independently from the asphalt plant and the RAC is produced which is to be used in the production of bitumen base.
 15. The hot asphalt recycling system according to claim 1, characterized in that in case of cooperation with asphalt plant; the RAC is produced which is to be used in the production of abrasion layer or binder.
 16. A hot asphalt recycling method applied in order to obtain RAC, to be used in the production of one of the asphalt layers, from the RAP, characterized by comprising the steps of: a) providing a body with a closed volume which is thermally and substantially insulated from the outer environment, b) advancing the RAP inside a transmission channel extending in a direction so as to define at least three corners inside said body, c) during said advancing process, circulating the hot air obtained from a hot air supply inside the inner volume of the body so as to provide heat transfer to a certain part of the RAP inside the transmission channel, d) circulating the hot air along the outer circumference of the body so as to provide heat transfer to a certain part of the RAP inside the transmission channel, e) circulating the hot air by directing the hot air inside the body so as to provide heat transfer to the RAP directly and indirectly, f) circulating the heated RAP inside the body so as to be directed to the accumulation reservoir, g) transferring the hot RAP inside the accumulation reservoir to a mixer at a predetermined arrangement, h) transferring new additional bitumen and optionally at least one chemical additive to said mixer at a predetermined arrangement, i) mixing the hot RAP material, new additional bitumen and optionally at least one chemical additive for a predetermined duration inside the mixer and discharging this mixture to the desired outer environment.
 17. The hot asphalt recycling method according to claim 16, characterized in that in said step (c), the hot air is partly circulated at the vicinity of the transmission channel so as to be substantially parallel to the transmission channel.
 18. The hot asphalt recycling method according to claim 16, characterized in that in said step (c), hot air is passed through the accumulation reservoir.
 19. The hot asphalt recycling method according to claim 16, characterized in that in said step (e), hot air is circulated so as to advance along a certain part of the diagonal edge of the body.
 20. The hot asphalt recycling method according to claim 16, characterized in that with respect to the operations options with or without asphalt plant, in said step (j), the material exiting from the mixer is directed to a silo or an asphalt plant.
 21. The hot asphalt recycling method according to claim 16, characterized in that in case of operation independent of the asphalt plant, the RAC material which will form the bitumen base is produced.
 22. The hot asphalt recycling method according to claim 16, characterized in that in case of cooperation with the asphalt plant, the RAC material which will form the abrasion or binder layer is produced. 